The present invention relates in general to a compressor and more particularly to a reciprocal motion type compressor generally and widely used for automotive vehicles, cars and the like.
A conventional reciprocal motion type compressor comprises a cylinder block defining a cylinder bore extending in an axial direction of the compressor. A piston is placed in the cylinder bore to be movable in the axial direction. The piston is reciprocally driven in the axial direction through a driving mechanism by an engine mounted on, for example, an automobile.
In the conventional reciprocal motion type compressor, the piston comprises a body member and a cover member coupled to the body member. The body member has a hollow portion at a rear portion thereof. The cover member has an insertion portion inserted into the hollow portion of the body member. After the insertion portion is inserted into the hollow portion, the body member and the cover member are fixed together by, for example, an electronic beam welding technique to form a coupling portion.
In the piston, there is a serious problem in mechanical strength in the coupling portion between the body member and the cover member in the axial direction. That is, the strength in the coupling portion is rather weak in the conventional structure. Therefore, the coupling portion has less durability relative to a repeated reciprocal movement of the compressor, particularly in a high speed operation of the compressor.